Structure and charge regulation mechanisms of Ti–Nb oxides modified by Sn for enhanced performance in Li-ion batteries

Ti₂Nb₁₀O₂₉ (TNO) is a promising anode material for lithium-ion batteries (LIBs) due to its high specific capacity and safety benefits. However, its practical application is hindered by poor intrinsic electrical and ionic conductivity. This study introduces a Sn modulation strategy to overcome these limitations. The modified Ti₂Nb_9.9Sn_0.1O₂₉ (Sn_0.1-TNO) exhibits an impressive rate capacity of 213.1 mAh·g⁻¹ at 10 C and retains 75.6% of this capacity after 1000 cycles at the same rate. Theoretical calculations and comprehensive characterizations reveal that Sn decoration introduces structural distortions, oxygen vacancies, and delocalized electrons into the TNO lattice, thereby narrowing the bandgap and transforming the material from an insulator to a semiconductor by increasing the availability of charge carriers. Consequently, this modification expands the Li⁺ storage space and reduces the Li⁺ diffusion barrier, facilitating faster ion transport and significantly enhancing the overall electrochemical performance of the TNO anode.